#include<reg52.h>
#define uint unsigned int
#define on  0
#define off 1

sbit fm = P2^3;


void delay(uint xms)
{
		uint i, j;
		for (i = xms; i > 0; i--)
				for (j = 122; j > 0; j--);
}

void main(void)
{
		int i = 0;
		while (1)
		{
				fm = on;
				delay(100);
				fm = off;
				delay(100);
		}
}